RFID tags are known in the art. These so-called tags often assume the form factor of a label or a literal “tag” but are also sometimes integrated with a host article and/or its packaging. RFID tags typically comprise an integrated circuit and one or more antennas. The integrated circuit typically carries out a variety of functions including modulating and demodulating radio frequency signals, data storage, and data processing. Some integrated circuits are active or self-powered (in whole or in part) while others are passive, being completely dependent upon an external power source (such as an RFID tag reader) to support their occasional functionality.
There are proposals to utilize RFID tags to individually identify individual items. The Electronic Product Code (EPC) as managed by EPCGlobal, Inc. represents one such effort in these regards. EPC-based RFID tags each have a unique serial number to thereby uniquely identify each tag and, by association, each item associated on a one-for-one basis with such tags. (The corresponding document entitled EPC Radio-Frequency Identity Protocols Class-1 Generation-2 UHF RFID Protocol for Communications at 860 MHz-960 MHz Version 1.0.9 is hereby fully incorporated herein by this reference.)
Many prior art methodologies provide for installing RFID tag readers (and in particular the antennas for such readers) at certain chokepoints through which most or all tagged items might be expected to pass. Other approaches are more aggressive and provide for effectively saturating a given facility with radio frequency energy in an effort to be able to read any RFID tag, any time, at any location within that facility. While effective to some degree, both such approaches are not wholly suitable to meet all needs of all potential users of such systems.
Building a system that attempts to illuminate every location within a given facility, for example, presents a very difficult challenge (in no small part due to maximum power limitations imposed on RFID tag readers by regulation and/or law and further by the fact that the operating environment will often tend to be highly dynamic with various bodies and surfaces moving from one location to another with corresponding effects upon the radio frequency environment from one spot to another). Accordingly, such an approach can represent both a considerable cost and also one that is subject to numerous frailties of the moment engendered by the dynamics of the application setting.
Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and/or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention. Certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. The terms and expressions used herein have the ordinary technical meaning as is accorded to such terms and expressions by persons skilled in the technical field as set forth above except where different specific meanings have otherwise been set forth herein.